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Notes: Abstract. A prolonged light treatment strongly increases responsivity to Pfr in many instances of phytochrome-controlled biogenesis of flavone or cyanidin glycosides. The present investigation deals with the question of whether light also leads to a corresponding increase of responsivity towards Pfr in such photoresponses which are not related to synthesis of flavonoid pigments in outer tissue layers of seedlings. Phytochrome-mediated accumulation of the chloroplast GPD (glyceraldehyde-3-phosphate dehydrogenase, EC 1.2.1.13) was chosen as a response and the milo shoot (Sorghum vulgare Pers. cv. Weider, hybrid) as an appropriate subject. It was found that responsivity towards Pfr is extremely weak in a dark-grown shoot while prolonged light pretreatments lead to a dramatic increase in responsivity. Blue and UV light are far more effective than red light in eliciting this effect within a few hours. High responsivity is only maintained in the light. When the seedlings are placed in darkness the level of responsivity drops rapidly with a half-life of the order of 2 h. The data allow more complete explanations for intriguing phenomena of plant life under natural light/dark conditions such as shade detection or sensing of light → dark transitions.

Notes: Seedlings of gymnosperms, unlike angiosperms, synthesize chlorophyll(ide) (Chl) in darkness (D). In Scots pine cotyledons (Pinus sylvestris L.) Chl accumulation ceases in D at a low level but Chl accumulation is strongly increased by light, red light (R) being more effective than blue light (B), whereas in Pinus maritima Chi synthesis is almost light-independent. In Scots pine the capacity to form Chl can be increased by R pulses, fully reversible by far-red light, demonstrating the involvement of phytochrome. However, when B- or R–grown seedlings were transferred to D, Chl accumulation stopped immediately irrespective of the level of Pfr (far-red light absorbing form of phytochrome), indicating that the conversion of protochlorophyllide (PChl) is light-dependent. Dose response curves in R and B and simultaneous irradiation with R and B show that R and B are perceived by separate photoreceptors. The immunodetected NADPH-dependent protochlorophyllide oxidoreductase (POR, EC 1.6.99.1), assumed to regulate light-dependent Chl synthesis in angiosperms, is not correlated with the capacity of gymnosperm Chi accumulation in darkness. While two FOR bands could be separated in extracts from dark grown material (38 and 36 kDa) of Pinus sylvestris and P. maritima, only the 38 kDa band disappeared consistently in the light. However. the significance of the more light resistant 36 kDa band for chlorophyll synthesis remains unclear as well.

Notes: Prolonged application of ammonium as a source of nitrogen leads to serious physiological and morphological disorders in many plants, including mustard (Sinapis alba L,) seedlings (ammonium toxicity syndrome). Ammonium tolerance was previously observed in mustard seedlings in the presence of considerable amounts of nitrate in the medium. In the present study, the question was addressed as to what extent accumulation of nitrate and ammonium occurs in the mustard seedling and how this relates to ammonium toxicity and tolerance. Emphasis was on light control of accumulation in the attached cotyledons. Both NQ3 and NH4 became strongly accumulated in the mustard cotyledons once the concentration in the medium exceeded 1 mM, In the cotyledons, we measured concentrations 〉 30 mM in the case of nitrate and 〉 50 mM in the case of ammonium 4 days after sowing. Accumulation of inorganic nitrogen in the mustard cotyledons did not depend on photosynthesis nor on intact chloroplasts. However, the rate of nitrate accumulation was strongly stimulated by light, operating through phytochrome, while ammonium accumulation was not affected by light in short-term experiments, i,e, within 24 h and only weakly (and probably indirectly) in long-term light.We conclude that strong interaction between NQ3 and NHJ is characteristic for accumulation of inorganic nitrogen. In the presence of NQ3, accumulation of NH3 is diminished and, to a lesser extent, vice versa. Using [15N]-labelling it was found that incorporation of inorganic nitrogen into organic compounds was stimulated strongly whenever nitrate and ammonium were provided simultaneously. It appears from the data that accumulation of nitrate is strictly controlled by the mustard cotyledons while the accumulation of ammonium is not. The data indicate that the level of ammonium is governed primarily by the rate of ammonium assimilation. Stimulation of ammonium assimilation by simultaneously applied nitrate appears to explain nitrate-mediated ammonium tolerance in the mustard plant.

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Notes: Appearance of nitrate reductase (NR, EC 1.6.6.1–3), nitrite reductase (NiR, EC 1.7.7.1) and glutamine synthetase (GS, EC 6.3.1.2) under the control of nitrate, ammonium and light was studied in roots, hypocotyls and needles (cotyledonary whorl) of the Scots pine (Pinus sylvestris L.) seedling. It was found that appearance of NiR was mainly controlled by nitrate whereas appearance of GS was strongly controlled by light. In principle, the NR activity level showed the same dependency on nitrate and light as that of NiR. In the root, both nitrate and ammonium had a stimulatory effect on GS activity whereas in the whorl the induction was minor. The level of NiR (NR) activity is high in the root and hypocotyl and low in the cotyledonary whorl, whereas the GS activity level per organ increases strongly from the root to the whorl. Thus, in any particular organ the operation of the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle is not closely connected to the operation of the nitrate reduction pathway. The strong control of GS/GOGAT by light and the minor sensitivity to induction by nitrate or ammonium indicate a major role of the GS/GOGAT cycle in reassimilation of endogeniously generated ammonium.

Notes: Seedlings of Scots pine (Pinus sylvestris L.) were grown on perlite for 21 days under controlled conditions. Apart from the water control, KNO3 (15 mM), (NH4)2SO4 (7.5 mM), and NH4NO3 (15 mM) were offered to study the effects of a high nitrogen supply on nitrogen assimilation. In some experiments 1.3 mM potassium was added to the basic ammonium solutions. In labelling studies nitrate and ammonium were 2.3 atom%15N-enriched. It was found that over the 21-day period approximately three times more ammonium-N was taken up than nitrate-N. However, nitrate and ammonium, applied simultaneously, were taken up to the same extent as if they were applied separately (additivity). The presence of K+ in the medium did not affect N-uptake. Among the soluble N-containing compounds nitrate, ammonium and 8 amino acids were quantified. It was found that assimilation of nitrate can cope with the uptake of NO−3 under all circumstances. Neither free nitrate nor ammonium or amino acids accumulated to an extent exceeding the values of water-grown seedlings. On the other hand, in case of high ammonium supply considerably more nitrogen was taken up than could be incorporated into nonsoluble N-containing substance (‘protein’). The remaining nitrogen was found to accumulate in intermediary storage pools (free NH4+, glutamine, asparagine, arginine). Part of this accumulated N could be incorporated into protein when potassium was offered in the nutrient solution. It is concluded that potassium is a requirement for a high rate of protein synthesis not only in crop plants but also in conifers.

Notes: In the present report the suggestion (Paech, K. 1950. Biochemie und Physiologie der sekundären Pflanzenstoffe. - Springer, Berlin, pp. 201–203) was tested that the photosynthetic apparatus requires light protection during the early phase of its development and that this is the reason (in a teleonomic sense) for the transient formation of large amounts of juvenile anthocyanin in outer tissue layers of seedlings and young leaves of deciduous trees and shrubs. Seedlings of two species (Sinapis alba L. and Sesamum indicum L.) which differ in their potential to produce anthocyanin were compared under identical light conditions. The results obtained are compatible with the idea that juvenile anthocyanins are involved in photoprotection. However, the experimental results also indicate that full photostability of the plastid is attained - irrespective of the presence or absence of anthocyanin - once a certain amount of chlorophyll has been accumulated. Thus, photosensitivity of a seedling under natural light conditions is restricted to an early phase of development prior to intense greening.

Notes: In many plant species, prolonged application of ammonium (NH4+) as a source of nitrogen results in physiological and morphological disorders (‘ammonium toxicity’). In the mustard (Sinapis alba L.) seedling we have previously observed particularly severe symptoms of ammonium toxicity in the absence of external nitrate (NO3-) or with increasing NH4+/NO3- ratios. In the present investigation we have studied the symptoms of this ‘toxicity’in more depth, i.e. at the morphological, plastidic, enzyme and mRNA levels, in an effort to elucidate the causation of the syndrome.It could be confirmed that the syndrome is specific for ammonium and is not caused by a surplus of nitrogen. The syndrome is caused neither by pH changes in the medium nor by non-specific osmotic effects. Furthermore, the syndrome is not causally related to the fact that nitrate reductase (NR; EC 1.6.6.1.) is induced by ammonium. Development of the syndrome requires neither photosynthesis nor intact plastids. Nevertheless, the plastids are severely affected by ammonium application as is anthocyanin synthesis.Enzymes are differently affected. Among the plastidic enzymes, levels of ribulose-1,5-bisphosphate carboxylase (RuBPCase; EC 4.1.1.39) and NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (NADP-GPD; EC 1.2.1.13) are strongly reduced and abundance of translatable mRNA of the small subunit of RuBPCase is decreased, whereas nitrite reductase (NIR; EC 1.7.7.1) is not affected. Among extraplastidic enzymes, the level of chalcone synthase (CHS; EC 2.3.1.74) is strongly reduced, the NAD-dependent glyceraldehyde-3-phosphate dehydrogenase (NADGPD; EC 1.2.1.12) level is unaffected, whereas the isocitrate lyase (ICL; EC 4.1.3.1) level is strongly promoted.The fat → carbohydrate transformation seems to be impaired by ammonium: fat degradation is reduced, starch accumulation is strongly inhibited and the levels of glucose and fructose are decreased.It appears from the present data and from results obtained in a companion study (U. Hecht and H. Mohr, in preparation) that the ammonium toxicity syndrome is detectable as soon as ammonium accumulation occurs in the plant. However, the actual mechanism through which the excess ammonium affects metabolism remains unclear at present.

Notes: Zusammenfassung Nach Diskussion der Literatur wird die Beobachtung einer tödlich verlaufenen Balanitis circinata erosiva, die mit einer akuten lokalisierten reaktiven histiocytären Reticulose der Inguinallymphknoten vergesellschaftet war, mitgeteilt, und der klinische Verlauf und der pathologischanatomische Befund ausführlich beschrieben. Auf die ätiologische Bedeutung der Anwesenheit pyogener Mikroorganismen im Präputialsack wird hingewiesen. Auf bestehende Ähnlichkeiten und Abgrenzungsmöglichkeiten zwischen der reaktiven histiocytären Reticulose und der klassischen Hodgkinschen Krankheit wird aufmerksam gemacht und eine Trennung beider Krankheitsbilder für notwendig erachtet. Als wesentlicher mitgestaltender Faktor der akuten reaktiven histiocytären Reticulose der regionären Lymphknoten, wird die myeloische Insuffizienz angesehen und daher für das anatomische granulomatöse Lymphknotensubstrat die Bezeichnung myelodys- bzw. myeloaplastogene reaktive histiocytäre Reticulose vorgeschlagen.

Notes: Zusammenfassung Nach einer eingehenden Erörterung des Schrifttums über den Errgernachweis der Boeckschen Krankheit, wird über den gelungenen Tuberkelbacillennachweis durch indirekte Kultur in 4 Beobachtungen von Boeckscher Krankheit aus Haut, Sputum und einer Tendovaginitis berichtet und der Infektionsablauf bei den geimpften Tieren analysiert. Aus dem Infektionsablauf der geimpften Meerschweinchen ist bemerkenswert, daß die Ausgangstiere der Beobachtungen 1–3 ohne Übergang in banale Tuberkulose nur geringe, vorwiegend lokalisierte Erscheinungen aufwiesen, während nach Passagen zunächst ausgedehntere nicht verkäsende, nach späteren Passagen auch verkäsende Erscheinungen auftraten. In der Beobachtung 4, einer Boeckschen Krankheit mit Übergang in banale Tuberkulose, kam es dagegen schon bei den Ausgangstieren zu verkäsenden Tuberkulosen. Der relativ seltene Nachweis von Tuberkelbacillen und das Auftreten banaler Tuberkulose bei Boeck-Kranken werden auf Grund der eigenen Ergebnisse so gedeutet, daß der Erreger der Boeckschen Krankheit der Tuberkelbacillus ist, der im Organismus des Boeck-Kranken auf Grund unspezifischer, wahrscheinlich konstitutionell bedingter Faktoren eine experimentell durch Tierpassagen oder unter gewissen Bedingungen spontan im menschlichen Organismus reversible Virulenzdrosselung erleidet.